Hi Ben,
> 1. As you found in Docs, native event portal is "Discontinued (no longer available)" ,
it not means the Portal is abandoned for Event manament, instead the Portal is built with new framework "Angular" to replace original Liquid js Portal,
it just changed front-end technology, while other back-end features such as Sign in are still available in Event Portal.
> 2. So customer self-service portal etc. are native type, and Event Portal is new type.
> 3. A free portals license is sometimes included with Dynamics 365 Marketing (depending on which license you have chosen),
but you are still limited to, at most, one free portal per tenant.
https://docs.microsoft.com/en-us/dynamics365/marketing/portal-optional#choose-whether-to-use-a-portal-when-setting-up-a-new-marketing-instance
> 4. In trial version, event website is hosted somewhere else, we can't manage it in Portal even if we have an unconfigured portal. (No such option in Portal management)
Try to open Dynamics 365 Marketing setup wizard in application confiugration and assign your portal to Marketing application again
https://docs.microsoft.com/en-us/dynamics365/marketing/purchase-setup#run-the-marketing-setup-wizard
If you still had encountered issue that Event Portal option was not available in paid version, please request a ticket for investigation.
https://admin.dynamics.com/?referer=mbssupport
Conclusion:
1. Event Portal is still available(based on your contry/region) for Dynamics 365 for Marketing without hosting it externally, but it's front-end technolgy has changed, so it couldn't be compatible with other portals.
2. You might buy another portal license if you have requirement for customer self-service type portal when you had configured a portal as event portal in Dynamcs 365 for Marketing application.
Regards,
Clofly
